The laryngeal mask airway reduces blood flow in the common carotid artery bulb.
OBJECTIVE
The introduction of the laryngeal mask airway (LMA) has had a major impact on anaesthetic practice in the last ten years. Previous authors have demonstrated pressures equivalent to mean arterial blood pressure within the cuff of the LMA. This study examined the effects of cuff inflation on the cross sectional area, flow and velocity of blood flow at the level of the carotid sinus.


METHODS
Seventeen patients scheduled to have LMAs inserted as part of routine anaesthetic management were recruited into the study. Measurements of the common carotid artery bulb area, peak velocity and blood flow were performed upon LMA cuff inflation and deflation using a 5 MHz pulse wave Doppler probe.


RESULTS
Deflation of the cuff resulted in an increase in the cross sectional area (from 0.58 +/- 0.05 to 0.64 +/- 0.04 cm2; P < 0.005), an increase in blood flow (from 65.6 +/- 5.6 to 73.9 +/- 5.6 cm3.sec-1; P < 0.05) and a slight but non significant increase in velocity of blood flow.


CONCLUSIONS
This study demonstrates that inflation of the cuff on the LMA results in a decrease in carotid bulb cross sectional area which results in a decrease in blood flow.
Colbert
S A
SA
Department of Anaesthesia, Mater Misericordiae Hospital, Dublin, Ireland.
O'Hanlon
D M
DM
Flanagan
F
F
Page
R
R
Moriarty
D C
DC
D000328:Adult; D000367:Age Factors; D000368:Aged; D000388:Air; D001161:Arteriosclerosis / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D002346:Carotid Sinus / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D017558:Elective Surgical Procedures; D004867:Equipment Design; D005260:Female; D006801:Humans; D017214:Laryngeal Masks / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow; D013499:Surface Properties; D018617:Ultrasonography, Doppler, Pulsed